Electronic smoking article

ABSTRACT

An electronic smoking article includes a heater and a liquid aerosol formulation. The heater is a coil heater. The liquid aerosol formulation includes at least one aerosol former, optionally water, nicotine and phosphoric acid. The phosphoric acid is included in an amount sufficient to substantially abate corrosion of the heater.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional application of U.S. application Ser.No. 14/332,823, filed Jul. 16, 2014, which claims priority under 35U.S.C. § 119(e) to U.S. provisional Application No. 61/856,923, filed onJul. 22, 2013, the entire content of each of which is incorporatedherein by reference thereto.

WORKING ENVIRONMENT

Electronic smoking articles include a liquid supply containing a liquidaerosol formulation and a heater. The liquid aerosol formulation caninclude aerosol formers such as propylene glycol and/or glycerin. It isknown that heating glycerin and/or propylene glycol beyond thetemperatures required to volatilize the liquid aerosol formulationproduces carbonyls.

Heaters formed of alloys including iron tend to corrode and rust overtime, producing iron oxide. Iron oxide tends to catalyze reactions withglycerin and/or propylene glycol such that carbonyls and/or carbonmonoxide are produced at temperatures below the temperature required tovolatilize the liquid aerosol formulation in electronic smokingarticles. Abatement of the production of carbonyls and/or carbonmonoxide at lower temperatures is desirable.

SUMMARY OF SELECTED FEATURES

An electronic smoking article, such as an electronic cigarette comprisesa heater and a liquid aerosol formulation. The liquid aerosolformulation comprises at least one aerosol former, optionally water,optionally nicotine, and phosphoric acid. The phosphoric acid isincluded in an amount sufficient to substantially abate corrosion of theheater. The heater element can be a wire heater, such as a wire coilformed of a material including iron.

In an embodiment, a method of abating formation of one or more ofcarbonyls, formaldehyde and carbon monoxide during smoking of anelectronic smoking article includes forming a liquid aerosol formulationincluding phosphoric acid in an amount sufficient to substantially abatecorrosion of the heater.

In another embodiment, a liquid aerosol formulation of an electronicsmoking article includes at least one aerosol former, optionally water,nicotine, and phosphoric acid in an amount sufficient to substantiallyabate corrosion of an iron-containing heater of an electronic smokingarticle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top planar view of an electronic smoking article in the formof an electronic cigarette according to a first embodiment.

FIG. 2 is a side cross-sectional view of the electronic smokinggenerating article shown in FIG. 1.

DETAILED DESCRIPTION

Heaters formed of metal alloys including iron tend to corrode and rustover time, producing iron oxide. During heating of a liquid aerosolformulation including at least one aerosol former, the iron oxide tendsto catalyze reactions with glycerin and/or propylene glycol such thatcarbonyls and/or carbon monoxide are produced at temperatures below thetemperature required to volatilize the liquid aerosol formulation. Anelectronic smoking article which abates corrosion of heaters formed ofmetal alloys including iron is described herein.

As used herein, the term “electronic smoking article” is inclusive ofall types of electronic smoking articles, regardless of form, size orshape, including electronic cigarettes, electronic cigars, electronicpipes, electronic hookahs and the like. The liquid aerosol formulationcan include nicotine or be nicotine free. Moreover, the liquid aerosolformulation can include tobacco flavors or instead, or in combinationinclude other suitable flavors.

Preferably, the electronic smoking article comprises a heater formed ofa metal alloy including iron and a liquid supply region (or liquidsupply) (or reservoir) containing a liquid aerosol formulation includingat least one aerosol former and food grade phosphoric acid. Preferably,the phosphoric acid is included in the liquid aerosol formulation in anamount sufficient to substantially prevent corrosion of a heater andavoid formation of one or more of formaldehyde, carbonyls and carbonmonoxide resulting from catalytic reactions between iron oxide and theat least one aerosol former.

The liquid aerosol formulation disclosed herein forms an aerosol whenheated in an electronic smoking article as shown in FIGS. 1 and 2. Theelectronic smoking article 60 comprises a replaceable cartridge (orfirst section) 70 and a reusable fixture (or second section) 72, whichare coupled together at a threaded joint 74 or by other convenience suchas a snug-fit, snap-fit, detent, clamp and/or clasp.

As shown in FIG. 2, the first section 70 can house a mouth-end insert20, a heater 319, a flexible, filamentary wick 328 and a reservoir 314as discussed in further detail below.

The second section 72 can house a power supply 12, control circuitry 11,and optionally a puff sensor 16. The threaded portion 74 of the secondsection 72 can be connected to a battery charger when not connected tothe first section 70 for use so as to charge the battery.

Preferably, the first section 70 and the second section 72 include anouter cylindrical housing 22 extending in a longitudinal direction alongthe length of the electronic smoking article 60. Moreover, in oneembodiment, the reservoir 314 of the first section 70 is refillable suchthat the first section 70 is reusable. In another embodiment, the firstsection 70 can also be replaceable so as to avoid the need for cleaningthe heater 319.

In the preferred embodiment, the electronic smoking article 60 includesa heater 319 and a filamentary wick 328 as shown in FIG. 2. The firstsection 70 includes an outer tube (or casing) 22 extending in alongitudinal direction and an inner tube (or chimney) 362 coaxiallypositioned within the outer tube 22. Preferably, a nose portion 361 ofan upstream gasket (or seal) 320 is fitted into an upstream end portion365 of the inner tube 362, while at the same time, an outer perimeter367 of the gasket 320 provides a liquid-tight seal with an interiorsurface 397 of the outer casing 22. The upstream gasket 320 alsoincludes a central, longitudinal air passage 315, which opens into aninterior of the inner tube 362 that defines a central channel 321. Atransverse channel 333 at an upstream portion of the gasket 320intersects and communicates with the central, longitudinal air passage315 of the gasket 320. This channel 333 assures communication betweenthe central, longitudinal air passage 315 and a space 335 definedbetween the gasket 320 and a threaded connection 74.

Preferably, a nose portion 393 of a downstream gasket 310 is fitted intoa downstream end portion 381 of the inner tube 362. An outer perimeter382 of the gasket 310 provides a substantially liquid-tight seal with aninterior surface 397 of the outer casing 22. The downstream gasket 310includes a central channel 384 disposed between the central passage 321of the inner tube 362 and the mouth end insert 20.

In this embodiment, the reservoir 314 is contained in an annulus betweenan inner tube 362 and an outer casing 22 and between the upstream gasket320 and the downstream gasket 310. Thus, the reservoir 314 at leastpartially surrounds the central air passage 321. The reservoir 314comprises the liquid aerosol formulation and optionally a liquid storagemedium (not shown) operable to store the liquid aerosol formulationtherein.

Preferably, the liquid storage medium is a fibrous material comprisingcotton, polyethylene, polyester, rayon and combinations thereof.Preferably, the fibers have a diameter ranging in size from about 6microns to about 15 microns (e.g., about 8 microns to about 12 micronsor about 9 microns to about 11 microns). In the alternative, thereservoir 314 may comprise a filled tank lacking a fibrous storagemedium and containing only liquid aerosol formulation.

Also preferably, the liquid aerosol formulation has a boiling pointsuitable for use in the electronic electronic smoking article 60, suchas an electronic cigarette. If the boiling point is too high, the heater319 will not be able to vaporize liquid in the filamentary wick 328.However, if the boiling point is too low, the liquid may vaporize evenwhen the heater 319 is not being activated.

Preferably, the heater 319 extends through the central air passage 321of the inner tube 362. The heater 319 is in contact with the filamentarywick 328, which preferably extends between opposing sections of thereservoir 314 so as to deliver the liquid aerosol formulation from thereservoir 314 to the heater 319.

Preferably, the filamentary wick 328 preferably comprises filamentshaving a capacity to draw a liquid, more preferably a bundle of glass(or ceramic) filaments and most preferably a bundle comprising a groupof windings of glass filaments, preferably three of such windings, allwhich arrangements are capable of drawing liquid via capillary actionvia interstitial spacings between the filaments. Preferably, thefilamentary wick 328 is flexible and includes three strands, each strandincluding a plurality of filaments.

Preferably, the electronic smoking article 60 also includes at least oneair inlet 440 arranged upstream of the heater 319. In the preferredembodiment, the at least one air inlet 440 includes one or two airinlets. Alternatively, there may be three, four, five or more airinlets. Altering the size and number of air inlets 440 can also aid inestablishing the resistance to draw of the electronic smoking article60.

The power supply 12 can include a battery arranged in the electronicsmoking article 60. The power supply 12 is operable to apply voltageacross the heater 319 associated with the filamentary wick 328. Thus,the heater 319 volatilizes the liquid aerosol formulation according to apower cycle of either a predetermined time period, such as a 2 to 10second period.

Preferably, electrical contacts between the heater 319 and theelectrical leads 26 are highly conductive and temperature resistantwhile the heater 319 is highly resistive so that heat generation occursprimarily along the heater 319 and not at the contacts.

The battery can be a Lithium-ion battery or one of its variants, forexample a Lithium-ion polymer battery. Alternatively, the battery may bea Nickel-metal hydride battery, a Nickel cadmium battery, aLithium-manganese battery, a Lithium-cobalt battery or a fuel cell. Inthat case, preferably, the electronic smoking article 60 is usable by asmoker (vaporer) until the energy in the power supply is depleted.Alternatively, the power supply 12 may be rechargeable and includecircuitry allowing the battery to be chargeable by an external chargingdevice. In that case, preferably the circuitry, when charged, providespower for a pre-determined number of puffs, after which the circuitrymust be re-connected to an external charging device.

Preferably, the electronic smoking article 60 of each embodiment alsoincludes control circuitry which can be on a printed circuit board 11.The control circuitry 11 can also include a heater activation light 27that is operable to glow when the heater 319 is activated. Preferably,the heater activation light 27 comprises at least one LED and is at anupstream end 28 of the electronic smoking article 60 so that the heateractivation light 27 illuminates a cap which takes on the appearance of aburning coal during a puff. Moreover, the heater activation light 27 canbe arranged to be visible to the smoker. In addition, the heateractivation light 27 can be utilized for smoking article systemdiagnostics. The light 27 can also be configured such that the smokercan activate and/or deactivate the light 27 when desired, such that thelight 27 would not activate during smoking (vaping) if desired.

The time-period of the electric current supply to the heater 319 may bepre-set depending on the amount of liquid desired to be vaporized. Thecontrol circuitry 11 can be programmable and can include an applicationspecific integrated circuit (ASIC). In other embodiments, the controlcircuitry 11 can include a microprocessor programmed to carry outfunctions.

As shown in FIG. 2, the electronic smoking article 60 further includes amouth-end insert 20 having at least two off-axis, preferably divergingoutlets 21. Preferably, the mouth-end insert 20 includes at least twodiverging outlets 21. (e.g, 3, 4, 5, or preferably 6 to 8 outlets ormore). Preferably, the outlets 21 of the mouth-end insert 20 are locatedat ends of off-axis passages 23 and are angled outwardly in relation tothe longitudinal direction of the electronic smoking article 60 (i.e.,divergently). As used herein, the term “off-axis” denotes at an angle tothe longitudinal direction of the electronic smoking article. Alsopreferably, the mouth-end insert (or flow guide) 20 includes outletsuniformly distributed around the mouth-end insert 20 so as tosubstantially uniformly distribute aerosol in a smoker's mouth duringuse. Thus, as the aerosol passes into a smoker's mouth, the aerosolenters the mouth and moves in different directions so as to provide afull mouth feel as compared to electronic smoking articles having anon-axis single orifice which directs the aerosol to a single location ina smoker's mouth.

In addition, the outlets 21 and off-axis passages 23 are arranged suchthat droplets of unaerosolized liquid aerosol formulation carried in theaerosol impact interior surfaces of the mouth-end insert 20 and/orinterior surfaces of the off-axis passages 23 such that the droplets areremoved or broken apart. In the preferred embodiment, the outlets 21 ofthe mouth-end insert 20 are located at the ends of the off-axis passages23 and are angled at 5 to 60° with respect to the central longitudinalaxis of the electronic smoking article 60 so as to more completelydistribute aerosol throughout a mouth of a smoker during use and toremove droplets.

Preferably, each outlet 21 has a diameter of about 0.015 inch to about0.090 inch (e.g., about 0.020 inch to about 0.040 inch or about 0.028inch to about 0.038 inch). The size of the outlets 21 and off-axispassages 23 along with the number of outlets 21 can be selected toadjust the resistance to draw (RTD) of the electronic smoking article60, if desired.

In a preferred embodiment, the electronic smoking article 60 is aboutthe same size as a conventional smoking article. In some embodiments,the electronic smoking article 60 can be about 80 mm to about 110 mmlong, preferably about 80 mm to about 100 mm long and about 7 mm toabout 8 mm in diameter. For example, in an embodiment, the electronicsmoking article is about 84 mm long and has a diameter of about 7.8 mm.

The outer cylindrical housing 22 of the electronic smoking article 60may be formed of any suitable material or combination of materials.Preferably, the outer cylindrical housing 22 is formed at leastpartially of metal and is part of the electrical circuit. The outercylindrical housing 22 can be any suitable color and/or can includegraphics or other indicia printed thereon. Although the housing isdescribed herein as cylindrical, other forms and shapes arecontemplated.

Preferably, at least one adhesive-backed label is applied to the outerhousing 22. The label completely circumscribes the electronic smokingarticle 60 and can be colored and/or textured to provide the look and/orfeel of a traditional cigarette. The label can include holes thereinwhich are sized and positioned so as to prevent blocking of the airinlets 440.

In the preferred embodiment, the heater 319 is a wire coil heater formedof a metal alloy including iron Examples of suitable electricallyresistive materials for use in making the heater 319 include titanium,zirconium, tantalum and metals from the platinum group. Examples ofsuitable metal alloys include stainless steel, nickel-, cobalt-,chromium-, aluminium- titanium- zirconium-, hafnium-, niobium-,molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese- andiron-containing alloys, and super-alloys based on nickel, iron, cobalt,stainless steel. For example, the heater can be formed of iron aluminideand other composite materials, the electrically resistive material mayoptionally be embedded in, encapsulated or coated with an insulatingmaterial or vice-versa, depending on the kinetics of energy transfer andthe external physicochemical properties required. In a preferredembodiment, the heater 319 may be constructed of iron-aluminide (e.g.,FeAl or Fe₃Al) or a nickel-chromium-iron.

During use, a heater coil including even a small amount of iron (e.g., awire coil formed of a nickel-chromium-iron alloy) may undergo corrosion,which is identified by visible pitting, discoloration and surfaceoxygen. While not wishing to be bound by theory, it is believed that thecorroded heater 319 reacts with aerosol formers in the reservoir 314 toform carbonyls, formaldehyde, and carbon monoxide during smoking.

It has been found that the addition of food grade phosphoric acid to theliquid aerosol formulation substantially abates potential corrosion ofthe iron-containing heater 319 and formation of iron oxide. Sinceformation of iron oxide is abated, iron oxide is not available tocatalyze reactions with aerosol formers resulting in the formation ofcarbonyls and carbon monoxide in the aerosol. Thus, in a preferredembodiment, the liquid aerosol formulation includes at least one aerosolformer, optionally water, optionally nicotine, and phosphoric acid in anamount sufficient to substantially prevent corrosion of the heater 319.

In the preferred embodiment, food grade phosphoric acid is added to theliquid aerosol formulation in an amount sufficient to substantiallyabate corrosion of the iron containing heater so as to reduce the amountof carbonyls and carbon monoxide formed during smoking as compared toliquid aerosol formulations excluding phosphoric acid. Preferably, thephosphoric acid is added in an amount ranging from about 0.1% to about5% (e.g., about 0.2% to about 5%, about 0.5% to about 4%, about 0.75% toabout 3%, or about 1% to about 2%). Preferably, the phosphoric acid isincluded in amount which is insufficient to alter the pH of the liquidaerosol formulation. While not wishing to be bound by theory, it isbelieved that acidic liquid aerosol formulations may promote charring ofthe heater, which can clog the heater and/or filamentary wick resultingin lower aerosol delivery and is therefore to be avoided or minimized.

Also preferably, the at least one aerosol former is selected from thegroup consisting of propylene glycol, glycerin and combinations thereof.Preferably, the at least one aerosol former is included in an amountranging from about 40% by weight based on the weight of the liquidformulation to about 90% by weight based on the weight of the liquidformulation (e.g., about 50% to about 80%, about 55% to about 75% orabout 60% to about 70%). Moreover, in one embodiment, the liquidformulation can include propylene glycol and glycerin included in aratio of about 3:2.

Preferably, the liquid formulation also includes water. Water can beincluded in an amount ranging from about 5% by weight based on theweight of the liquid formulation to about 40% by weight based on theweight of the liquid formulation, more preferably in an amount rangingfrom about 10% by weight based on the weight of the liquid formulationto about 15% by weight based on the weight of the liquid formulation.

The liquid aerosol formulation optionally includes at least oneflavorant in an amount up to about 15% by weight (e.g., about 0.2% toabout 15%, about 1% to about 12%, about 2% to about 10%, or about 5% toabout 8%). The at least one flavorant can be a natural flavorant or anartificial flavorant. Preferably, the at least one flavorant is selectedfrom the group consisting of tobacco flavor, menthol, wintergreen,peppermint, herb flavors, fruit flavors, nut flavors, liquor flavors,and combinations thereof.

Preferably, the liquid aerosol formulation also includes nicotine. Thenicotine is included in the liquid aerosol formulation in an amountranging from about 1% by weight to about 10% by weight (e.g., about 2%to about 9%, about 2% to about 8%, about 2% to about 6%). In analternative embodiment, the liquid aerosol formulation can benicotine-free.

When the word “about” is used in this specification in connection with anumerical value, it is intended that the associated numerical valueinclude a tolerance of ±10% around the stated numerical value. Moreover,when reference is made to percentages in this specification, it isintended that those percentages are based on weight, i.e., weightpercentages. The expression “up to” includes amounts of zero to theexpressed upper limit and all values therebetween. When ranges arespecified, the range includes all values therebetween such as incrementsof 0.1%.

Moreover, when the words “generally” and “substantially” are used inconnection with geometric shapes, it is intended that precision of thegeometric shape is not required but that latitude for the shape iswithin the scope of the disclosure. When used with geometric terms, thewords “generally” and “substantially” are intended to encompass not onlyfeatures which meet the strict definitions but also features whichfairly approximate the strict definitions.

It will now be apparent that a new, improved, and nonobvious electronicsmoking article, liquid aerosol formulation and method has beendescribed in this specification with sufficient particularity as to beunderstood by one of ordinary skill in the art. Moreover, it will beapparent to those skilled in the art that numerous modifications,variations, substitutions, and equivalents exist for features of theelectronic smoking article, liquid aerosol formulation and method whichdo not materially depart from the spirit and scope of the invention.Accordingly, it is expressly intended that all such modifications,variations, substitutions, and equivalents which fall within the spiritand scope of the invention as defined by the appended claims shall beembraced by the appended claims.

1. A method of forming a pre-vapor formulation of an electronic vapingdevice comprising: forming a pre-vapor formulation; and addingphosphoric acid to the pre-vapor formulation in an amount ranging fromabout 0.1% by weight to about 5% by weight
 2. The method of claim 1,wherein the forming comprises: combining water and at least one vaporformer.
 3. The method of claim 2, wherein the forming further comprises:adding nicotine to the pre-vapor formulation.
 4. The method of claim 3,wherein the adding nicotine comprises: adding nicotine in an amountranging from about 1% by weight to about 10% by weight.
 5. The method ofclaim 2, wherein the combining water comprises: combining water withpropylene glycol, glycerin, or both propylene glycol and glycerin. 6.The method of claim 2, wherein the forming comprises: adding at leastone vapor former in an amount ranging from about 40% by weight to about90% by weight.
 7. The method of claim 1, wherein the forming comprises:combining glycerin and propylene glycol in a ratio of at least about2:3.
 8. The method of claim 1, further comprising: adding at least oneflavorant to the pre-vapor formulation.
 9. The method of claim 8,wherein the adding at least one flavorant comprises: adding the at leastone flavorant in an amount ranging from about 2% to about 15% by weight.